In the competitive industry of golf club design, distance and accuracy are two of the most important performance factors that help define the desirability of a metal wood type golf club. Although some may argue that the look, feel, and sound of a golf club may influence their opinion of a golf club; there is no arguing that the performance factors play a major role in determining the desirability of a golf club. The performance factors of maximizing distance while maintaining accuracy becomes even more prevalent in a metal wood type golf club head. Unlike iron type golf club heads where accuracy of a golf shot clearly trumps the distance benefits gained by any individual golf club, metal wood type golf club heads are designed to allow a golfer to hit the golf ball as far as possible in and as straight as possible.
In order to maximize distance while maintaining accuracy of a metal wood type golf club head, metal wood type golf clubs have been designed with the objective of maximizing the distance of a golf ball struck by a golf club head close to the geometric center of the golf club head. This geometric center of the golf club head, due to the inherent laws of physics, may generally produce a golf shot that maximizes the distance by reducing the energy loss between the golf ball and the golf club head. In order to quantify this value, the United States Golf Association (USGA), in conjunction with the golfing industry, have come up with various methods such as the calculation the Coefficient of Restitution (COR) or the calculation of the Characteristic Time (CT) as ways to quantify the rebounding characteristic of a golf ball after it impacts a golf club head.
U.S. Pat. No. 6,390,933 to Galloway et al. ('933 Patent) discusses one of the methods to increase the COR of a golf club head by disclosing a golf club head having a coefficient of restitution greater than 0.845 and a durability to withstand 2000 impacts with a golf ball at 110 miles per hour, wherein the club head may be composed of three pieces, a face, a sole, and a crown. More specifically, the '933 Patent discloses a golf club head that may be composed of a titanium material, having a volume in the range of 175 cubic centimeters to 400 cubic centimeters, a weight in the range of 165 grams to 300 grams, and a striking plate surface area in the range of 4.00 square inches to 7.50 square inches.
Focusing on accuracy instead of distance, U.S. Patent Publication No. 2004/0116202 to Lin ('202 Patent Publication), discusses a method to increase the accuracy of a golf club head by disclosing a golf club head having a plurality of holes around the periphery of the club head, so that when the club head hits the golf ball, most of the vibration waves and sound waves generated are dispersed out of these holes thus improving accuracy of the direction of the striking golf ball.
However, upon closer examination, we can see that developments in maximizing distance while maintaining accuracy of a metal wood type golf club head are premised upon the fact that the golfer be capable of hitting the golf ball at the sweet spot. The sweet spot, generally coinciding with the geometric center of the golf club, may cover such a small area of the striking face of the golf club head, it may be difficult for the average golfer to consistently strike a golf ball in the sweet spot. Hence, in addition to the performance factors mentioned above, it may also be desirable to increase the size of this sweet spot, so an average golfer may obtain the design benefits of maximizing the distance and accuracy of the golf club head without having to strike the golf ball perfectly every time.
In order to address the issue that the golfer may not always strike a golf ball at the center of the striking face, the industry has attempted to experiment striking faces having different variable face thickness. In fact, different golf club heads may even have multiple zones with different thicknesses to improve the size of the sweet spot to allow the average golfer to achieve maximum results even when they do not hit the golf ball at the center of the striking face. Despite the fact that these methodologies may improve the size of the club head, they do not take into consideration the performance benefits that may be achieved by adjusting the actual geometry of the striking face of the golf club head.
It can be seen from above there is a need in the field for a golf club head that is capable of utilizing the geometry of the striking face of the golf club head itself to increase the size of the sweet spot of the golf club head. More specifically, there is a need in the field for a golf club head that allows the average golfer to achieve performance benefits similar to those achievable by the skilled professional golfer even when they do not strike the golf ball directly at the center of the golf club head.